1 //===- PassManagerBuilder.cpp - Build Standard Pass -----------------------===//
2 //
3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4 // See https://llvm.org/LICENSE.txt for license information.
5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6 //
7 //===----------------------------------------------------------------------===//
8 //
9 // This file defines the PassManagerBuilder class, which is used to set up a
10 // "standard" optimization sequence suitable for languages like C and C++.
11 //
12 //===----------------------------------------------------------------------===//
13 
14 #include "llvm/Transforms/IPO/PassManagerBuilder.h"
15 #include "llvm-c/Transforms/PassManagerBuilder.h"
16 #include "llvm/ADT/STLExtras.h"
17 #include "llvm/ADT/SmallVector.h"
18 #include "llvm/Analysis/CFLAndersAliasAnalysis.h"
19 #include "llvm/Analysis/CFLSteensAliasAnalysis.h"
20 #include "llvm/Analysis/GlobalsModRef.h"
21 #include "llvm/Analysis/InlineCost.h"
22 #include "llvm/Analysis/ScopedNoAliasAA.h"
23 #include "llvm/Analysis/TargetLibraryInfo.h"
24 #include "llvm/Analysis/TypeBasedAliasAnalysis.h"
25 #include "llvm/IR/LegacyPassManager.h"
26 #include "llvm/IR/Verifier.h"
27 #include "llvm/Support/CommandLine.h"
28 #include "llvm/Support/ManagedStatic.h"
29 #include "llvm/Target/CGPassBuilderOption.h"
30 #include "llvm/Transforms/AggressiveInstCombine/AggressiveInstCombine.h"
31 #include "llvm/Transforms/IPO.h"
32 #include "llvm/Transforms/IPO/Attributor.h"
33 #include "llvm/Transforms/IPO/ForceFunctionAttrs.h"
34 #include "llvm/Transforms/IPO/FunctionAttrs.h"
35 #include "llvm/Transforms/IPO/InferFunctionAttrs.h"
36 #include "llvm/Transforms/InstCombine/InstCombine.h"
37 #include "llvm/Transforms/Instrumentation.h"
38 #include "llvm/Transforms/Scalar.h"
39 #include "llvm/Transforms/Scalar/GVN.h"
40 #include "llvm/Transforms/Scalar/LICM.h"
41 #include "llvm/Transforms/Scalar/LoopUnrollPass.h"
42 #include "llvm/Transforms/Scalar/SimpleLoopUnswitch.h"
43 #include "llvm/Transforms/Utils.h"
44 #include "llvm/Transforms/Vectorize.h"
45 
46 using namespace llvm;
47 
48 namespace llvm {
49 cl::opt<bool> RunPartialInlining("enable-partial-inlining", cl::init(false),
50                                  cl::Hidden, cl::ZeroOrMore,
51                                  cl::desc("Run Partial inlinining pass"));
52 
53 static cl::opt<bool>
54 UseGVNAfterVectorization("use-gvn-after-vectorization",
55   cl::init(false), cl::Hidden,
56   cl::desc("Run GVN instead of Early CSE after vectorization passes"));
57 
58 cl::opt<bool> ExtraVectorizerPasses(
59     "extra-vectorizer-passes", cl::init(false), cl::Hidden,
60     cl::desc("Run cleanup optimization passes after vectorization."));
61 
62 static cl::opt<bool>
63 RunLoopRerolling("reroll-loops", cl::Hidden,
64                  cl::desc("Run the loop rerolling pass"));
65 
66 cl::opt<bool> RunNewGVN("enable-newgvn", cl::init(false), cl::Hidden,
67                         cl::desc("Run the NewGVN pass"));
68 
69 // Experimental option to use CFL-AA
70 static cl::opt<::CFLAAType>
71     UseCFLAA("use-cfl-aa", cl::init(::CFLAAType::None), cl::Hidden,
72              cl::desc("Enable the new, experimental CFL alias analysis"),
73              cl::values(clEnumValN(::CFLAAType::None, "none", "Disable CFL-AA"),
74                         clEnumValN(::CFLAAType::Steensgaard, "steens",
75                                    "Enable unification-based CFL-AA"),
76                         clEnumValN(::CFLAAType::Andersen, "anders",
77                                    "Enable inclusion-based CFL-AA"),
78                         clEnumValN(::CFLAAType::Both, "both",
79                                    "Enable both variants of CFL-AA")));
80 
81 cl::opt<bool> EnableLoopInterchange(
82     "enable-loopinterchange", cl::init(false), cl::Hidden,
83     cl::desc("Enable the experimental LoopInterchange Pass"));
84 
85 cl::opt<bool> EnableUnrollAndJam("enable-unroll-and-jam", cl::init(false),
86                                  cl::Hidden,
87                                  cl::desc("Enable Unroll And Jam Pass"));
88 
89 cl::opt<bool> EnableLoopFlatten("enable-loop-flatten", cl::init(false),
90                                 cl::Hidden,
91                                 cl::desc("Enable the LoopFlatten Pass"));
92 
93 cl::opt<bool> EnableDFAJumpThreading("enable-dfa-jump-thread",
94                                      cl::desc("Enable DFA jump threading."),
95                                      cl::init(false), cl::Hidden);
96 
97 static cl::opt<bool>
98     EnablePrepareForThinLTO("prepare-for-thinlto", cl::init(false), cl::Hidden,
99                             cl::desc("Enable preparation for ThinLTO."));
100 
101 static cl::opt<bool>
102     EnablePerformThinLTO("perform-thinlto", cl::init(false), cl::Hidden,
103                          cl::desc("Enable performing ThinLTO."));
104 
105 cl::opt<bool> EnableHotColdSplit("hot-cold-split", cl::init(false),
106     cl::ZeroOrMore, cl::desc("Enable hot-cold splitting pass"));
107 
108 cl::opt<bool> EnableIROutliner("ir-outliner", cl::init(false), cl::Hidden,
109     cl::desc("Enable ir outliner pass"));
110 
111 static cl::opt<bool> UseLoopVersioningLICM(
112     "enable-loop-versioning-licm", cl::init(false), cl::Hidden,
113     cl::desc("Enable the experimental Loop Versioning LICM pass"));
114 
115 cl::opt<bool>
116     DisablePreInliner("disable-preinline", cl::init(false), cl::Hidden,
117                       cl::desc("Disable pre-instrumentation inliner"));
118 
119 cl::opt<int> PreInlineThreshold(
120     "preinline-threshold", cl::Hidden, cl::init(75), cl::ZeroOrMore,
121     cl::desc("Control the amount of inlining in pre-instrumentation inliner "
122              "(default = 75)"));
123 
124 cl::opt<bool>
125     EnableGVNHoist("enable-gvn-hoist", cl::init(false), cl::ZeroOrMore,
126                    cl::desc("Enable the GVN hoisting pass (default = off)"));
127 
128 static cl::opt<bool>
129     DisableLibCallsShrinkWrap("disable-libcalls-shrinkwrap", cl::init(false),
130                               cl::Hidden,
131                               cl::desc("Disable shrink-wrap library calls"));
132 
133 static cl::opt<bool> EnableSimpleLoopUnswitch(
134     "enable-simple-loop-unswitch", cl::init(false), cl::Hidden,
135     cl::desc("Enable the simple loop unswitch pass. Also enables independent "
136              "cleanup passes integrated into the loop pass manager pipeline."));
137 
138 cl::opt<bool>
139     EnableGVNSink("enable-gvn-sink", cl::init(false), cl::ZeroOrMore,
140                   cl::desc("Enable the GVN sinking pass (default = off)"));
141 
142 // This option is used in simplifying testing SampleFDO optimizations for
143 // profile loading.
144 cl::opt<bool>
145     EnableCHR("enable-chr", cl::init(true), cl::Hidden,
146               cl::desc("Enable control height reduction optimization (CHR)"));
147 
148 cl::opt<bool> FlattenedProfileUsed(
149     "flattened-profile-used", cl::init(false), cl::Hidden,
150     cl::desc("Indicate the sample profile being used is flattened, i.e., "
151              "no inline hierachy exists in the profile. "));
152 
153 cl::opt<bool> EnableOrderFileInstrumentation(
154     "enable-order-file-instrumentation", cl::init(false), cl::Hidden,
155     cl::desc("Enable order file instrumentation (default = off)"));
156 
157 cl::opt<bool> EnableMatrix(
158     "enable-matrix", cl::init(false), cl::Hidden,
159     cl::desc("Enable lowering of the matrix intrinsics"));
160 
161 cl::opt<bool> EnableConstraintElimination(
162     "enable-constraint-elimination", cl::init(false), cl::Hidden,
163     cl::desc(
164         "Enable pass to eliminate conditions based on linear constraints."));
165 
166 cl::opt<bool> EnableFunctionSpecialization(
167     "enable-function-specialization", cl::init(false), cl::Hidden,
168     cl::desc("Enable Function Specialization pass"));
169 
170 cl::opt<AttributorRunOption> AttributorRun(
171     "attributor-enable", cl::Hidden, cl::init(AttributorRunOption::NONE),
172     cl::desc("Enable the attributor inter-procedural deduction pass."),
173     cl::values(clEnumValN(AttributorRunOption::ALL, "all",
174                           "enable all attributor runs"),
175                clEnumValN(AttributorRunOption::MODULE, "module",
176                           "enable module-wide attributor runs"),
177                clEnumValN(AttributorRunOption::CGSCC, "cgscc",
178                           "enable call graph SCC attributor runs"),
179                clEnumValN(AttributorRunOption::NONE, "none",
180                           "disable attributor runs")));
181 
182 extern cl::opt<bool> EnableKnowledgeRetention;
183 } // namespace llvm
184 
185 PassManagerBuilder::PassManagerBuilder() {
186     OptLevel = 2;
187     SizeLevel = 0;
188     LibraryInfo = nullptr;
189     Inliner = nullptr;
190     DisableUnrollLoops = false;
191     SLPVectorize = false;
192     LoopVectorize = true;
193     LoopsInterleaved = true;
194     RerollLoops = RunLoopRerolling;
195     NewGVN = RunNewGVN;
196     LicmMssaOptCap = SetLicmMssaOptCap;
197     LicmMssaNoAccForPromotionCap = SetLicmMssaNoAccForPromotionCap;
198     DisableGVNLoadPRE = false;
199     ForgetAllSCEVInLoopUnroll = ForgetSCEVInLoopUnroll;
200     VerifyInput = false;
201     VerifyOutput = false;
202     MergeFunctions = false;
203     PrepareForLTO = false;
204     EnablePGOInstrGen = false;
205     EnablePGOCSInstrGen = false;
206     EnablePGOCSInstrUse = false;
207     PGOInstrGen = "";
208     PGOInstrUse = "";
209     PGOSampleUse = "";
210     PrepareForThinLTO = EnablePrepareForThinLTO;
211     PerformThinLTO = EnablePerformThinLTO;
212     DivergentTarget = false;
213     CallGraphProfile = true;
214 }
215 
216 PassManagerBuilder::~PassManagerBuilder() {
217   delete LibraryInfo;
218   delete Inliner;
219 }
220 
221 /// Set of global extensions, automatically added as part of the standard set.
222 static ManagedStatic<
223     SmallVector<std::tuple<PassManagerBuilder::ExtensionPointTy,
224                            PassManagerBuilder::ExtensionFn,
225                            PassManagerBuilder::GlobalExtensionID>,
226                 8>>
227     GlobalExtensions;
228 static PassManagerBuilder::GlobalExtensionID GlobalExtensionsCounter;
229 
230 /// Check if GlobalExtensions is constructed and not empty.
231 /// Since GlobalExtensions is a managed static, calling 'empty()' will trigger
232 /// the construction of the object.
233 static bool GlobalExtensionsNotEmpty() {
234   return GlobalExtensions.isConstructed() && !GlobalExtensions->empty();
235 }
236 
237 PassManagerBuilder::GlobalExtensionID
238 PassManagerBuilder::addGlobalExtension(PassManagerBuilder::ExtensionPointTy Ty,
239                                        PassManagerBuilder::ExtensionFn Fn) {
240   auto ExtensionID = GlobalExtensionsCounter++;
241   GlobalExtensions->push_back(std::make_tuple(Ty, std::move(Fn), ExtensionID));
242   return ExtensionID;
243 }
244 
245 void PassManagerBuilder::removeGlobalExtension(
246     PassManagerBuilder::GlobalExtensionID ExtensionID) {
247   // RegisterStandardPasses may try to call this function after GlobalExtensions
248   // has already been destroyed; doing so should not generate an error.
249   if (!GlobalExtensions.isConstructed())
250     return;
251 
252   auto GlobalExtension =
253       llvm::find_if(*GlobalExtensions, [ExtensionID](const auto &elem) {
254         return std::get<2>(elem) == ExtensionID;
255       });
256   assert(GlobalExtension != GlobalExtensions->end() &&
257          "The extension ID to be removed should always be valid.");
258 
259   GlobalExtensions->erase(GlobalExtension);
260 }
261 
262 void PassManagerBuilder::addExtension(ExtensionPointTy Ty, ExtensionFn Fn) {
263   Extensions.push_back(std::make_pair(Ty, std::move(Fn)));
264 }
265 
266 void PassManagerBuilder::addExtensionsToPM(ExtensionPointTy ETy,
267                                            legacy::PassManagerBase &PM) const {
268   if (GlobalExtensionsNotEmpty()) {
269     for (auto &Ext : *GlobalExtensions) {
270       if (std::get<0>(Ext) == ETy)
271         std::get<1>(Ext)(*this, PM);
272     }
273   }
274   for (unsigned i = 0, e = Extensions.size(); i != e; ++i)
275     if (Extensions[i].first == ETy)
276       Extensions[i].second(*this, PM);
277 }
278 
279 void PassManagerBuilder::addInitialAliasAnalysisPasses(
280     legacy::PassManagerBase &PM) const {
281   switch (UseCFLAA) {
282   case ::CFLAAType::Steensgaard:
283     PM.add(createCFLSteensAAWrapperPass());
284     break;
285   case ::CFLAAType::Andersen:
286     PM.add(createCFLAndersAAWrapperPass());
287     break;
288   case ::CFLAAType::Both:
289     PM.add(createCFLSteensAAWrapperPass());
290     PM.add(createCFLAndersAAWrapperPass());
291     break;
292   default:
293     break;
294   }
295 
296   // Add TypeBasedAliasAnalysis before BasicAliasAnalysis so that
297   // BasicAliasAnalysis wins if they disagree. This is intended to help
298   // support "obvious" type-punning idioms.
299   PM.add(createTypeBasedAAWrapperPass());
300   PM.add(createScopedNoAliasAAWrapperPass());
301 }
302 
303 void PassManagerBuilder::populateFunctionPassManager(
304     legacy::FunctionPassManager &FPM) {
305   addExtensionsToPM(EP_EarlyAsPossible, FPM);
306 
307   // Add LibraryInfo if we have some.
308   if (LibraryInfo)
309     FPM.add(new TargetLibraryInfoWrapperPass(*LibraryInfo));
310 
311   // The backends do not handle matrix intrinsics currently.
312   // Make sure they are also lowered in O0.
313   // FIXME: A lightweight version of the pass should run in the backend
314   //        pipeline on demand.
315   if (EnableMatrix && OptLevel == 0)
316     FPM.add(createLowerMatrixIntrinsicsMinimalPass());
317 
318   if (OptLevel == 0) return;
319 
320   addInitialAliasAnalysisPasses(FPM);
321 
322   // Lower llvm.expect to metadata before attempting transforms.
323   // Compare/branch metadata may alter the behavior of passes like SimplifyCFG.
324   FPM.add(createLowerExpectIntrinsicPass());
325   FPM.add(createCFGSimplificationPass());
326   FPM.add(createSROAPass());
327   FPM.add(createEarlyCSEPass());
328 }
329 
330 void PassManagerBuilder::addFunctionSimplificationPasses(
331     legacy::PassManagerBase &MPM) {
332   // Start of function pass.
333   // Break up aggregate allocas, using SSAUpdater.
334   assert(OptLevel >= 1 && "Calling function optimizer with no optimization level!");
335   MPM.add(createSROAPass());
336   MPM.add(createEarlyCSEPass(true /* Enable mem-ssa. */)); // Catch trivial redundancies
337   if (EnableKnowledgeRetention)
338     MPM.add(createAssumeSimplifyPass());
339 
340   if (OptLevel > 1) {
341     if (EnableGVNHoist)
342       MPM.add(createGVNHoistPass());
343     if (EnableGVNSink) {
344       MPM.add(createGVNSinkPass());
345       MPM.add(createCFGSimplificationPass(
346           SimplifyCFGOptions().convertSwitchRangeToICmp(true)));
347     }
348   }
349 
350   if (EnableConstraintElimination)
351     MPM.add(createConstraintEliminationPass());
352 
353   if (OptLevel > 1) {
354     // Speculative execution if the target has divergent branches; otherwise nop.
355     MPM.add(createSpeculativeExecutionIfHasBranchDivergencePass());
356 
357     MPM.add(createJumpThreadingPass());         // Thread jumps.
358     MPM.add(createCorrelatedValuePropagationPass()); // Propagate conditionals
359   }
360   MPM.add(
361       createCFGSimplificationPass(SimplifyCFGOptions().convertSwitchRangeToICmp(
362           true))); // Merge & remove BBs
363   // Combine silly seq's
364   if (OptLevel > 2)
365     MPM.add(createAggressiveInstCombinerPass());
366   MPM.add(createInstructionCombiningPass());
367   if (SizeLevel == 0 && !DisableLibCallsShrinkWrap)
368     MPM.add(createLibCallsShrinkWrapPass());
369   addExtensionsToPM(EP_Peephole, MPM);
370 
371   // TODO: Investigate the cost/benefit of tail call elimination on debugging.
372   if (OptLevel > 1)
373     MPM.add(createTailCallEliminationPass()); // Eliminate tail calls
374   MPM.add(
375       createCFGSimplificationPass(SimplifyCFGOptions().convertSwitchRangeToICmp(
376           true)));                            // Merge & remove BBs
377   MPM.add(createReassociatePass());           // Reassociate expressions
378 
379   // The matrix extension can introduce large vector operations early, which can
380   // benefit from running vector-combine early on.
381   if (EnableMatrix)
382     MPM.add(createVectorCombinePass());
383 
384   // Begin the loop pass pipeline.
385   if (EnableSimpleLoopUnswitch) {
386     // The simple loop unswitch pass relies on separate cleanup passes. Schedule
387     // them first so when we re-process a loop they run before other loop
388     // passes.
389     MPM.add(createLoopInstSimplifyPass());
390     MPM.add(createLoopSimplifyCFGPass());
391   }
392   // Try to remove as much code from the loop header as possible,
393   // to reduce amount of IR that will have to be duplicated. However,
394   // do not perform speculative hoisting the first time as LICM
395   // will destroy metadata that may not need to be destroyed if run
396   // after loop rotation.
397   // TODO: Investigate promotion cap for O1.
398   MPM.add(createLICMPass(LicmMssaOptCap, LicmMssaNoAccForPromotionCap,
399                          /*AllowSpeculation=*/false));
400   // Rotate Loop - disable header duplication at -Oz
401   MPM.add(createLoopRotatePass(SizeLevel == 2 ? 0 : -1, PrepareForLTO));
402   // TODO: Investigate promotion cap for O1.
403   MPM.add(createLICMPass(LicmMssaOptCap, LicmMssaNoAccForPromotionCap,
404                          /*AllowSpeculation=*/true));
405   if (EnableSimpleLoopUnswitch)
406     MPM.add(createSimpleLoopUnswitchLegacyPass());
407   else
408     MPM.add(createLoopUnswitchPass(SizeLevel || OptLevel < 3, DivergentTarget));
409   // FIXME: We break the loop pass pipeline here in order to do full
410   // simplifycfg. Eventually loop-simplifycfg should be enhanced to replace the
411   // need for this.
412   MPM.add(createCFGSimplificationPass(
413       SimplifyCFGOptions().convertSwitchRangeToICmp(true)));
414   MPM.add(createInstructionCombiningPass());
415   // We resume loop passes creating a second loop pipeline here.
416   if (EnableLoopFlatten) {
417     MPM.add(createLoopFlattenPass()); // Flatten loops
418     MPM.add(createLoopSimplifyCFGPass());
419   }
420   MPM.add(createLoopIdiomPass());             // Recognize idioms like memset.
421   MPM.add(createIndVarSimplifyPass());        // Canonicalize indvars
422   addExtensionsToPM(EP_LateLoopOptimizations, MPM);
423   MPM.add(createLoopDeletionPass());          // Delete dead loops
424 
425   if (EnableLoopInterchange)
426     MPM.add(createLoopInterchangePass()); // Interchange loops
427 
428   // Unroll small loops and perform peeling.
429   MPM.add(createSimpleLoopUnrollPass(OptLevel, DisableUnrollLoops,
430                                      ForgetAllSCEVInLoopUnroll));
431   addExtensionsToPM(EP_LoopOptimizerEnd, MPM);
432   // This ends the loop pass pipelines.
433 
434   // Break up allocas that may now be splittable after loop unrolling.
435   MPM.add(createSROAPass());
436 
437   if (OptLevel > 1) {
438     MPM.add(createMergedLoadStoreMotionPass()); // Merge ld/st in diamonds
439     MPM.add(NewGVN ? createNewGVNPass()
440                    : createGVNPass(DisableGVNLoadPRE)); // Remove redundancies
441   }
442   MPM.add(createSCCPPass());                  // Constant prop with SCCP
443 
444   if (EnableConstraintElimination)
445     MPM.add(createConstraintEliminationPass());
446 
447   // Delete dead bit computations (instcombine runs after to fold away the dead
448   // computations, and then ADCE will run later to exploit any new DCE
449   // opportunities that creates).
450   MPM.add(createBitTrackingDCEPass());        // Delete dead bit computations
451 
452   // Run instcombine after redundancy elimination to exploit opportunities
453   // opened up by them.
454   MPM.add(createInstructionCombiningPass());
455   addExtensionsToPM(EP_Peephole, MPM);
456   if (OptLevel > 1) {
457     if (EnableDFAJumpThreading && SizeLevel == 0)
458       MPM.add(createDFAJumpThreadingPass());
459 
460     MPM.add(createJumpThreadingPass());         // Thread jumps
461     MPM.add(createCorrelatedValuePropagationPass());
462   }
463   MPM.add(createAggressiveDCEPass()); // Delete dead instructions
464 
465   MPM.add(createMemCpyOptPass());               // Remove memcpy / form memset
466   // TODO: Investigate if this is too expensive at O1.
467   if (OptLevel > 1) {
468     MPM.add(createDeadStoreEliminationPass());  // Delete dead stores
469     MPM.add(createLICMPass(LicmMssaOptCap, LicmMssaNoAccForPromotionCap,
470                            /*AllowSpeculation=*/true));
471   }
472 
473   addExtensionsToPM(EP_ScalarOptimizerLate, MPM);
474 
475   if (RerollLoops)
476     MPM.add(createLoopRerollPass());
477 
478   // Merge & remove BBs and sink & hoist common instructions.
479   MPM.add(createCFGSimplificationPass(
480       SimplifyCFGOptions().hoistCommonInsts(true).sinkCommonInsts(true)));
481   // Clean up after everything.
482   MPM.add(createInstructionCombiningPass());
483   addExtensionsToPM(EP_Peephole, MPM);
484 
485   if (EnableCHR && OptLevel >= 3 &&
486       (!PGOInstrUse.empty() || !PGOSampleUse.empty() || EnablePGOCSInstrGen))
487     MPM.add(createControlHeightReductionLegacyPass());
488 }
489 
490 /// FIXME: Should LTO cause any differences to this set of passes?
491 void PassManagerBuilder::addVectorPasses(legacy::PassManagerBase &PM,
492                                          bool IsFullLTO) {
493   PM.add(createLoopVectorizePass(!LoopsInterleaved, !LoopVectorize));
494 
495   if (IsFullLTO) {
496     // The vectorizer may have significantly shortened a loop body; unroll
497     // again. Unroll small loops to hide loop backedge latency and saturate any
498     // parallel execution resources of an out-of-order processor. We also then
499     // need to clean up redundancies and loop invariant code.
500     // FIXME: It would be really good to use a loop-integrated instruction
501     // combiner for cleanup here so that the unrolling and LICM can be pipelined
502     // across the loop nests.
503     // We do UnrollAndJam in a separate LPM to ensure it happens before unroll
504     if (EnableUnrollAndJam && !DisableUnrollLoops)
505       PM.add(createLoopUnrollAndJamPass(OptLevel));
506     PM.add(createLoopUnrollPass(OptLevel, DisableUnrollLoops,
507                                 ForgetAllSCEVInLoopUnroll));
508     PM.add(createWarnMissedTransformationsPass());
509   }
510 
511   if (!IsFullLTO) {
512     // Eliminate loads by forwarding stores from the previous iteration to loads
513     // of the current iteration.
514     PM.add(createLoopLoadEliminationPass());
515   }
516   // Cleanup after the loop optimization passes.
517   PM.add(createInstructionCombiningPass());
518 
519   if (OptLevel > 1 && ExtraVectorizerPasses) {
520     // At higher optimization levels, try to clean up any runtime overlap and
521     // alignment checks inserted by the vectorizer. We want to track correlated
522     // runtime checks for two inner loops in the same outer loop, fold any
523     // common computations, hoist loop-invariant aspects out of any outer loop,
524     // and unswitch the runtime checks if possible. Once hoisted, we may have
525     // dead (or speculatable) control flows or more combining opportunities.
526     PM.add(createEarlyCSEPass());
527     PM.add(createCorrelatedValuePropagationPass());
528     PM.add(createInstructionCombiningPass());
529     PM.add(createLICMPass(LicmMssaOptCap, LicmMssaNoAccForPromotionCap,
530                           /*AllowSpeculation=*/true));
531     PM.add(createLoopUnswitchPass(SizeLevel || OptLevel < 3, DivergentTarget));
532     PM.add(createCFGSimplificationPass(
533         SimplifyCFGOptions().convertSwitchRangeToICmp(true)));
534     PM.add(createInstructionCombiningPass());
535   }
536 
537   // Now that we've formed fast to execute loop structures, we do further
538   // optimizations. These are run afterward as they might block doing complex
539   // analyses and transforms such as what are needed for loop vectorization.
540 
541   // Cleanup after loop vectorization, etc. Simplification passes like CVP and
542   // GVN, loop transforms, and others have already run, so it's now better to
543   // convert to more optimized IR using more aggressive simplify CFG options.
544   // The extra sinking transform can create larger basic blocks, so do this
545   // before SLP vectorization.
546   PM.add(createCFGSimplificationPass(SimplifyCFGOptions()
547                                          .forwardSwitchCondToPhi(true)
548                                          .convertSwitchRangeToICmp(true)
549                                          .convertSwitchToLookupTable(true)
550                                          .needCanonicalLoops(false)
551                                          .hoistCommonInsts(true)
552                                          .sinkCommonInsts(true)));
553 
554   if (IsFullLTO) {
555     PM.add(createSCCPPass());                 // Propagate exposed constants
556     PM.add(createInstructionCombiningPass()); // Clean up again
557     PM.add(createBitTrackingDCEPass());
558   }
559 
560   // Optimize parallel scalar instruction chains into SIMD instructions.
561   if (SLPVectorize) {
562     PM.add(createSLPVectorizerPass());
563     if (OptLevel > 1 && ExtraVectorizerPasses)
564       PM.add(createEarlyCSEPass());
565   }
566 
567   // Enhance/cleanup vector code.
568   PM.add(createVectorCombinePass());
569 
570   if (!IsFullLTO) {
571     addExtensionsToPM(EP_Peephole, PM);
572     PM.add(createInstructionCombiningPass());
573 
574     if (EnableUnrollAndJam && !DisableUnrollLoops) {
575       // Unroll and Jam. We do this before unroll but need to be in a separate
576       // loop pass manager in order for the outer loop to be processed by
577       // unroll and jam before the inner loop is unrolled.
578       PM.add(createLoopUnrollAndJamPass(OptLevel));
579     }
580 
581     // Unroll small loops
582     PM.add(createLoopUnrollPass(OptLevel, DisableUnrollLoops,
583                                 ForgetAllSCEVInLoopUnroll));
584 
585     if (!DisableUnrollLoops) {
586       // LoopUnroll may generate some redundency to cleanup.
587       PM.add(createInstructionCombiningPass());
588 
589       // Runtime unrolling will introduce runtime check in loop prologue. If the
590       // unrolled loop is a inner loop, then the prologue will be inside the
591       // outer loop. LICM pass can help to promote the runtime check out if the
592       // checked value is loop invariant.
593       PM.add(createLICMPass(LicmMssaOptCap, LicmMssaNoAccForPromotionCap,
594                             /*AllowSpeculation=*/true));
595     }
596 
597     PM.add(createWarnMissedTransformationsPass());
598   }
599 
600   // After vectorization and unrolling, assume intrinsics may tell us more
601   // about pointer alignments.
602   PM.add(createAlignmentFromAssumptionsPass());
603 
604   if (IsFullLTO)
605     PM.add(createInstructionCombiningPass());
606 }
607 
608 void PassManagerBuilder::populateModulePassManager(
609     legacy::PassManagerBase &MPM) {
610   MPM.add(createAnnotation2MetadataLegacyPass());
611 
612   if (!PGOSampleUse.empty()) {
613     MPM.add(createPruneEHPass());
614     // In ThinLTO mode, when flattened profile is used, all the available
615     // profile information will be annotated in PreLink phase so there is
616     // no need to load the profile again in PostLink.
617     if (!(FlattenedProfileUsed && PerformThinLTO))
618       MPM.add(createSampleProfileLoaderPass(PGOSampleUse));
619   }
620 
621   // Allow forcing function attributes as a debugging and tuning aid.
622   MPM.add(createForceFunctionAttrsLegacyPass());
623 
624   // If all optimizations are disabled, just run the always-inline pass and,
625   // if enabled, the function merging pass.
626   if (OptLevel == 0) {
627     if (Inliner) {
628       MPM.add(Inliner);
629       Inliner = nullptr;
630     }
631 
632     // FIXME: The BarrierNoopPass is a HACK! The inliner pass above implicitly
633     // creates a CGSCC pass manager, but we don't want to add extensions into
634     // that pass manager. To prevent this we insert a no-op module pass to reset
635     // the pass manager to get the same behavior as EP_OptimizerLast in non-O0
636     // builds. The function merging pass is
637     if (MergeFunctions)
638       MPM.add(createMergeFunctionsPass());
639     else if (GlobalExtensionsNotEmpty() || !Extensions.empty())
640       MPM.add(createBarrierNoopPass());
641 
642     if (PerformThinLTO) {
643       MPM.add(createLowerTypeTestsPass(nullptr, nullptr, true));
644       // Drop available_externally and unreferenced globals. This is necessary
645       // with ThinLTO in order to avoid leaving undefined references to dead
646       // globals in the object file.
647       MPM.add(createEliminateAvailableExternallyPass());
648       MPM.add(createGlobalDCEPass());
649     }
650 
651     addExtensionsToPM(EP_EnabledOnOptLevel0, MPM);
652 
653     if (PrepareForLTO || PrepareForThinLTO) {
654       MPM.add(createCanonicalizeAliasesPass());
655       // Rename anon globals to be able to export them in the summary.
656       // This has to be done after we add the extensions to the pass manager
657       // as there could be passes (e.g. Adddress sanitizer) which introduce
658       // new unnamed globals.
659       MPM.add(createNameAnonGlobalPass());
660     }
661 
662     MPM.add(createAnnotationRemarksLegacyPass());
663     return;
664   }
665 
666   // Add LibraryInfo if we have some.
667   if (LibraryInfo)
668     MPM.add(new TargetLibraryInfoWrapperPass(*LibraryInfo));
669 
670   addInitialAliasAnalysisPasses(MPM);
671 
672   // For ThinLTO there are two passes of indirect call promotion. The
673   // first is during the compile phase when PerformThinLTO=false and
674   // intra-module indirect call targets are promoted. The second is during
675   // the ThinLTO backend when PerformThinLTO=true, when we promote imported
676   // inter-module indirect calls. For that we perform indirect call promotion
677   // earlier in the pass pipeline, here before globalopt. Otherwise imported
678   // available_externally functions look unreferenced and are removed.
679   if (PerformThinLTO) {
680     MPM.add(createLowerTypeTestsPass(nullptr, nullptr, true));
681   }
682 
683   // For SamplePGO in ThinLTO compile phase, we do not want to unroll loops
684   // as it will change the CFG too much to make the 2nd profile annotation
685   // in backend more difficult.
686   bool PrepareForThinLTOUsingPGOSampleProfile =
687       PrepareForThinLTO && !PGOSampleUse.empty();
688   if (PrepareForThinLTOUsingPGOSampleProfile)
689     DisableUnrollLoops = true;
690 
691   // Infer attributes about declarations if possible.
692   MPM.add(createInferFunctionAttrsLegacyPass());
693 
694   // Infer attributes on declarations, call sites, arguments, etc.
695   if (AttributorRun & AttributorRunOption::MODULE)
696     MPM.add(createAttributorLegacyPass());
697 
698   addExtensionsToPM(EP_ModuleOptimizerEarly, MPM);
699 
700   if (OptLevel > 2)
701     MPM.add(createCallSiteSplittingPass());
702 
703   // Propage constant function arguments by specializing the functions.
704   if (OptLevel > 2 && EnableFunctionSpecialization)
705     MPM.add(createFunctionSpecializationPass());
706 
707   MPM.add(createIPSCCPPass());          // IP SCCP
708   MPM.add(createCalledValuePropagationPass());
709 
710   MPM.add(createGlobalOptimizerPass()); // Optimize out global vars
711   // Promote any localized global vars.
712   MPM.add(createPromoteMemoryToRegisterPass());
713 
714   MPM.add(createDeadArgEliminationPass()); // Dead argument elimination
715 
716   MPM.add(createInstructionCombiningPass()); // Clean up after IPCP & DAE
717   addExtensionsToPM(EP_Peephole, MPM);
718   MPM.add(
719       createCFGSimplificationPass(SimplifyCFGOptions().convertSwitchRangeToICmp(
720           true))); // Clean up after IPCP & DAE
721 
722   // We add a module alias analysis pass here. In part due to bugs in the
723   // analysis infrastructure this "works" in that the analysis stays alive
724   // for the entire SCC pass run below.
725   MPM.add(createGlobalsAAWrapperPass());
726 
727   // Start of CallGraph SCC passes.
728   MPM.add(createPruneEHPass()); // Remove dead EH info
729   bool RunInliner = false;
730   if (Inliner) {
731     MPM.add(Inliner);
732     Inliner = nullptr;
733     RunInliner = true;
734   }
735 
736   // Infer attributes on declarations, call sites, arguments, etc. for an SCC.
737   if (AttributorRun & AttributorRunOption::CGSCC)
738     MPM.add(createAttributorCGSCCLegacyPass());
739 
740   // Try to perform OpenMP specific optimizations. This is a (quick!) no-op if
741   // there are no OpenMP runtime calls present in the module.
742   if (OptLevel > 1)
743     MPM.add(createOpenMPOptCGSCCLegacyPass());
744 
745   MPM.add(createPostOrderFunctionAttrsLegacyPass());
746   if (OptLevel > 2)
747     MPM.add(createArgumentPromotionPass()); // Scalarize uninlined fn args
748 
749   addExtensionsToPM(EP_CGSCCOptimizerLate, MPM);
750   addFunctionSimplificationPasses(MPM);
751 
752   // FIXME: This is a HACK! The inliner pass above implicitly creates a CGSCC
753   // pass manager that we are specifically trying to avoid. To prevent this
754   // we must insert a no-op module pass to reset the pass manager.
755   MPM.add(createBarrierNoopPass());
756 
757   if (RunPartialInlining)
758     MPM.add(createPartialInliningPass());
759 
760   if (OptLevel > 1 && !PrepareForLTO && !PrepareForThinLTO)
761     // Remove avail extern fns and globals definitions if we aren't
762     // compiling an object file for later LTO. For LTO we want to preserve
763     // these so they are eligible for inlining at link-time. Note if they
764     // are unreferenced they will be removed by GlobalDCE later, so
765     // this only impacts referenced available externally globals.
766     // Eventually they will be suppressed during codegen, but eliminating
767     // here enables more opportunity for GlobalDCE as it may make
768     // globals referenced by available external functions dead
769     // and saves running remaining passes on the eliminated functions.
770     MPM.add(createEliminateAvailableExternallyPass());
771 
772   if (EnableOrderFileInstrumentation)
773     MPM.add(createInstrOrderFilePass());
774 
775   MPM.add(createReversePostOrderFunctionAttrsPass());
776 
777   // The inliner performs some kind of dead code elimination as it goes,
778   // but there are cases that are not really caught by it. We might
779   // at some point consider teaching the inliner about them, but it
780   // is OK for now to run GlobalOpt + GlobalDCE in tandem as their
781   // benefits generally outweight the cost, making the whole pipeline
782   // faster.
783   if (RunInliner) {
784     MPM.add(createGlobalOptimizerPass());
785     MPM.add(createGlobalDCEPass());
786   }
787 
788   // If we are planning to perform ThinLTO later, let's not bloat the code with
789   // unrolling/vectorization/... now. We'll first run the inliner + CGSCC passes
790   // during ThinLTO and perform the rest of the optimizations afterward.
791   if (PrepareForThinLTO) {
792     // Ensure we perform any last passes, but do so before renaming anonymous
793     // globals in case the passes add any.
794     addExtensionsToPM(EP_OptimizerLast, MPM);
795     MPM.add(createCanonicalizeAliasesPass());
796     // Rename anon globals to be able to export them in the summary.
797     MPM.add(createNameAnonGlobalPass());
798     return;
799   }
800 
801   if (PerformThinLTO)
802     // Optimize globals now when performing ThinLTO, this enables more
803     // optimizations later.
804     MPM.add(createGlobalOptimizerPass());
805 
806   // Scheduling LoopVersioningLICM when inlining is over, because after that
807   // we may see more accurate aliasing. Reason to run this late is that too
808   // early versioning may prevent further inlining due to increase of code
809   // size. By placing it just after inlining other optimizations which runs
810   // later might get benefit of no-alias assumption in clone loop.
811   if (UseLoopVersioningLICM) {
812     MPM.add(createLoopVersioningLICMPass());    // Do LoopVersioningLICM
813     MPM.add(createLICMPass(LicmMssaOptCap, LicmMssaNoAccForPromotionCap,
814                            /*AllowSpeculation=*/true));
815   }
816 
817   // We add a fresh GlobalsModRef run at this point. This is particularly
818   // useful as the above will have inlined, DCE'ed, and function-attr
819   // propagated everything. We should at this point have a reasonably minimal
820   // and richly annotated call graph. By computing aliasing and mod/ref
821   // information for all local globals here, the late loop passes and notably
822   // the vectorizer will be able to use them to help recognize vectorizable
823   // memory operations.
824   //
825   // Note that this relies on a bug in the pass manager which preserves
826   // a module analysis into a function pass pipeline (and throughout it) so
827   // long as the first function pass doesn't invalidate the module analysis.
828   // Thus both Float2Int and LoopRotate have to preserve AliasAnalysis for
829   // this to work. Fortunately, it is trivial to preserve AliasAnalysis
830   // (doing nothing preserves it as it is required to be conservatively
831   // correct in the face of IR changes).
832   MPM.add(createGlobalsAAWrapperPass());
833 
834   MPM.add(createFloat2IntPass());
835   MPM.add(createLowerConstantIntrinsicsPass());
836 
837   if (EnableMatrix) {
838     MPM.add(createLowerMatrixIntrinsicsPass());
839     // CSE the pointer arithmetic of the column vectors.  This allows alias
840     // analysis to establish no-aliasing between loads and stores of different
841     // columns of the same matrix.
842     MPM.add(createEarlyCSEPass(false));
843   }
844 
845   addExtensionsToPM(EP_VectorizerStart, MPM);
846 
847   // Re-rotate loops in all our loop nests. These may have fallout out of
848   // rotated form due to GVN or other transformations, and the vectorizer relies
849   // on the rotated form. Disable header duplication at -Oz.
850   MPM.add(createLoopRotatePass(SizeLevel == 2 ? 0 : -1, PrepareForLTO));
851 
852   // Distribute loops to allow partial vectorization.  I.e. isolate dependences
853   // into separate loop that would otherwise inhibit vectorization.  This is
854   // currently only performed for loops marked with the metadata
855   // llvm.loop.distribute=true or when -enable-loop-distribute is specified.
856   MPM.add(createLoopDistributePass());
857 
858   addVectorPasses(MPM, /* IsFullLTO */ false);
859 
860   // FIXME: We shouldn't bother with this anymore.
861   MPM.add(createStripDeadPrototypesPass()); // Get rid of dead prototypes
862 
863   // GlobalOpt already deletes dead functions and globals, at -O2 try a
864   // late pass of GlobalDCE.  It is capable of deleting dead cycles.
865   if (OptLevel > 1) {
866     MPM.add(createGlobalDCEPass());         // Remove dead fns and globals.
867     MPM.add(createConstantMergePass());     // Merge dup global constants
868   }
869 
870   // See comment in the new PM for justification of scheduling splitting at
871   // this stage (\ref buildModuleSimplificationPipeline).
872   if (EnableHotColdSplit && !(PrepareForLTO || PrepareForThinLTO))
873     MPM.add(createHotColdSplittingPass());
874 
875   if (EnableIROutliner)
876     MPM.add(createIROutlinerPass());
877 
878   if (MergeFunctions)
879     MPM.add(createMergeFunctionsPass());
880 
881   // Add Module flag "CG Profile" based on Branch Frequency Information.
882   if (CallGraphProfile)
883     MPM.add(createCGProfileLegacyPass());
884 
885   // LoopSink pass sinks instructions hoisted by LICM, which serves as a
886   // canonicalization pass that enables other optimizations. As a result,
887   // LoopSink pass needs to be a very late IR pass to avoid undoing LICM
888   // result too early.
889   MPM.add(createLoopSinkPass());
890   // Get rid of LCSSA nodes.
891   MPM.add(createInstSimplifyLegacyPass());
892 
893   // This hoists/decomposes div/rem ops. It should run after other sink/hoist
894   // passes to avoid re-sinking, but before SimplifyCFG because it can allow
895   // flattening of blocks.
896   MPM.add(createDivRemPairsPass());
897 
898   // LoopSink (and other loop passes since the last simplifyCFG) might have
899   // resulted in single-entry-single-exit or empty blocks. Clean up the CFG.
900   MPM.add(createCFGSimplificationPass(
901       SimplifyCFGOptions().convertSwitchRangeToICmp(true)));
902 
903   addExtensionsToPM(EP_OptimizerLast, MPM);
904 
905   if (PrepareForLTO) {
906     MPM.add(createCanonicalizeAliasesPass());
907     // Rename anon globals to be able to handle them in the summary
908     MPM.add(createNameAnonGlobalPass());
909   }
910 
911   MPM.add(createAnnotationRemarksLegacyPass());
912 }
913 
914 void PassManagerBuilder::addLTOOptimizationPasses(legacy::PassManagerBase &PM) {
915   // Load sample profile before running the LTO optimization pipeline.
916   if (!PGOSampleUse.empty()) {
917     PM.add(createPruneEHPass());
918     PM.add(createSampleProfileLoaderPass(PGOSampleUse));
919   }
920 
921   // Remove unused virtual tables to improve the quality of code generated by
922   // whole-program devirtualization and bitset lowering.
923   PM.add(createGlobalDCEPass());
924 
925   // Provide AliasAnalysis services for optimizations.
926   addInitialAliasAnalysisPasses(PM);
927 
928   // Allow forcing function attributes as a debugging and tuning aid.
929   PM.add(createForceFunctionAttrsLegacyPass());
930 
931   // Infer attributes about declarations if possible.
932   PM.add(createInferFunctionAttrsLegacyPass());
933 
934   if (OptLevel > 1) {
935     // Split call-site with more constrained arguments.
936     PM.add(createCallSiteSplittingPass());
937 
938     // Propage constant function arguments by specializing the functions.
939     if (EnableFunctionSpecialization && OptLevel > 2)
940       PM.add(createFunctionSpecializationPass());
941 
942     // Propagate constants at call sites into the functions they call.  This
943     // opens opportunities for globalopt (and inlining) by substituting function
944     // pointers passed as arguments to direct uses of functions.
945     PM.add(createIPSCCPPass());
946 
947     // Attach metadata to indirect call sites indicating the set of functions
948     // they may target at run-time. This should follow IPSCCP.
949     PM.add(createCalledValuePropagationPass());
950 
951     // Infer attributes on declarations, call sites, arguments, etc.
952     if (AttributorRun & AttributorRunOption::MODULE)
953       PM.add(createAttributorLegacyPass());
954   }
955 
956   // Infer attributes about definitions. The readnone attribute in particular is
957   // required for virtual constant propagation.
958   PM.add(createPostOrderFunctionAttrsLegacyPass());
959   PM.add(createReversePostOrderFunctionAttrsPass());
960 
961   // Split globals using inrange annotations on GEP indices. This can help
962   // improve the quality of generated code when virtual constant propagation or
963   // control flow integrity are enabled.
964   PM.add(createGlobalSplitPass());
965 
966   // Apply whole-program devirtualization and virtual constant propagation.
967   PM.add(createWholeProgramDevirtPass(ExportSummary, nullptr));
968 
969   // That's all we need at opt level 1.
970   if (OptLevel == 1)
971     return;
972 
973   // Now that we internalized some globals, see if we can hack on them!
974   PM.add(createGlobalOptimizerPass());
975   // Promote any localized global vars.
976   PM.add(createPromoteMemoryToRegisterPass());
977 
978   // Linking modules together can lead to duplicated global constants, only
979   // keep one copy of each constant.
980   PM.add(createConstantMergePass());
981 
982   // Remove unused arguments from functions.
983   PM.add(createDeadArgEliminationPass());
984 
985   // Reduce the code after globalopt and ipsccp.  Both can open up significant
986   // simplification opportunities, and both can propagate functions through
987   // function pointers.  When this happens, we often have to resolve varargs
988   // calls, etc, so let instcombine do this.
989   if (OptLevel > 2)
990     PM.add(createAggressiveInstCombinerPass());
991   PM.add(createInstructionCombiningPass());
992   addExtensionsToPM(EP_Peephole, PM);
993 
994   // Inline small functions
995   bool RunInliner = Inliner;
996   if (RunInliner) {
997     PM.add(Inliner);
998     Inliner = nullptr;
999   }
1000 
1001   PM.add(createPruneEHPass());   // Remove dead EH info.
1002 
1003   // Infer attributes on declarations, call sites, arguments, etc. for an SCC.
1004   if (AttributorRun & AttributorRunOption::CGSCC)
1005     PM.add(createAttributorCGSCCLegacyPass());
1006 
1007   // Try to perform OpenMP specific optimizations. This is a (quick!) no-op if
1008   // there are no OpenMP runtime calls present in the module.
1009   if (OptLevel > 1)
1010     PM.add(createOpenMPOptCGSCCLegacyPass());
1011 
1012   // Optimize globals again if we ran the inliner.
1013   if (RunInliner)
1014     PM.add(createGlobalOptimizerPass());
1015   PM.add(createGlobalDCEPass()); // Remove dead functions.
1016 
1017   // If we didn't decide to inline a function, check to see if we can
1018   // transform it to pass arguments by value instead of by reference.
1019   PM.add(createArgumentPromotionPass());
1020 
1021   // The IPO passes may leave cruft around.  Clean up after them.
1022   PM.add(createInstructionCombiningPass());
1023   addExtensionsToPM(EP_Peephole, PM);
1024   PM.add(createJumpThreadingPass(/*FreezeSelectCond*/ true));
1025 
1026   // Break up allocas
1027   PM.add(createSROAPass());
1028 
1029   // LTO provides additional opportunities for tailcall elimination due to
1030   // link-time inlining, and visibility of nocapture attribute.
1031   if (OptLevel > 1)
1032     PM.add(createTailCallEliminationPass());
1033 
1034   // Infer attributes on declarations, call sites, arguments, etc.
1035   PM.add(createPostOrderFunctionAttrsLegacyPass()); // Add nocapture.
1036   // Run a few AA driven optimizations here and now, to cleanup the code.
1037   PM.add(createGlobalsAAWrapperPass()); // IP alias analysis.
1038 
1039   PM.add(createLICMPass(LicmMssaOptCap, LicmMssaNoAccForPromotionCap,
1040                         /*AllowSpeculation=*/true));
1041   PM.add(NewGVN ? createNewGVNPass()
1042                 : createGVNPass(DisableGVNLoadPRE)); // Remove redundancies.
1043   PM.add(createMemCpyOptPass());            // Remove dead memcpys.
1044 
1045   // Nuke dead stores.
1046   PM.add(createDeadStoreEliminationPass());
1047   PM.add(createMergedLoadStoreMotionPass()); // Merge ld/st in diamonds.
1048 
1049   // More loops are countable; try to optimize them.
1050   if (EnableLoopFlatten)
1051     PM.add(createLoopFlattenPass());
1052   PM.add(createIndVarSimplifyPass());
1053   PM.add(createLoopDeletionPass());
1054   if (EnableLoopInterchange)
1055     PM.add(createLoopInterchangePass());
1056 
1057   if (EnableConstraintElimination)
1058     PM.add(createConstraintEliminationPass());
1059 
1060   // Unroll small loops and perform peeling.
1061   PM.add(createSimpleLoopUnrollPass(OptLevel, DisableUnrollLoops,
1062                                     ForgetAllSCEVInLoopUnroll));
1063   PM.add(createLoopDistributePass());
1064 
1065   addVectorPasses(PM, /* IsFullLTO */ true);
1066 
1067   addExtensionsToPM(EP_Peephole, PM);
1068 
1069   PM.add(createJumpThreadingPass(/*FreezeSelectCond*/ true));
1070 }
1071 
1072 void PassManagerBuilder::addLateLTOOptimizationPasses(
1073     legacy::PassManagerBase &PM) {
1074   // See comment in the new PM for justification of scheduling splitting at
1075   // this stage (\ref buildLTODefaultPipeline).
1076   if (EnableHotColdSplit)
1077     PM.add(createHotColdSplittingPass());
1078 
1079   // Delete basic blocks, which optimization passes may have killed.
1080   PM.add(
1081       createCFGSimplificationPass(SimplifyCFGOptions().hoistCommonInsts(true)));
1082 
1083   // Drop bodies of available externally objects to improve GlobalDCE.
1084   PM.add(createEliminateAvailableExternallyPass());
1085 
1086   // Now that we have optimized the program, discard unreachable functions.
1087   PM.add(createGlobalDCEPass());
1088 
1089   // FIXME: this is profitable (for compiler time) to do at -O0 too, but
1090   // currently it damages debug info.
1091   if (MergeFunctions)
1092     PM.add(createMergeFunctionsPass());
1093 }
1094 
1095 LLVMPassManagerBuilderRef LLVMPassManagerBuilderCreate() {
1096   PassManagerBuilder *PMB = new PassManagerBuilder();
1097   return wrap(PMB);
1098 }
1099 
1100 void LLVMPassManagerBuilderDispose(LLVMPassManagerBuilderRef PMB) {
1101   PassManagerBuilder *Builder = unwrap(PMB);
1102   delete Builder;
1103 }
1104 
1105 void
1106 LLVMPassManagerBuilderSetOptLevel(LLVMPassManagerBuilderRef PMB,
1107                                   unsigned OptLevel) {
1108   PassManagerBuilder *Builder = unwrap(PMB);
1109   Builder->OptLevel = OptLevel;
1110 }
1111 
1112 void
1113 LLVMPassManagerBuilderSetSizeLevel(LLVMPassManagerBuilderRef PMB,
1114                                    unsigned SizeLevel) {
1115   PassManagerBuilder *Builder = unwrap(PMB);
1116   Builder->SizeLevel = SizeLevel;
1117 }
1118 
1119 void
1120 LLVMPassManagerBuilderSetDisableUnitAtATime(LLVMPassManagerBuilderRef PMB,
1121                                             LLVMBool Value) {
1122   // NOTE: The DisableUnitAtATime switch has been removed.
1123 }
1124 
1125 void
1126 LLVMPassManagerBuilderSetDisableUnrollLoops(LLVMPassManagerBuilderRef PMB,
1127                                             LLVMBool Value) {
1128   PassManagerBuilder *Builder = unwrap(PMB);
1129   Builder->DisableUnrollLoops = Value;
1130 }
1131 
1132 void
1133 LLVMPassManagerBuilderSetDisableSimplifyLibCalls(LLVMPassManagerBuilderRef PMB,
1134                                                  LLVMBool Value) {
1135   // NOTE: The simplify-libcalls pass has been removed.
1136 }
1137 
1138 void
1139 LLVMPassManagerBuilderUseInlinerWithThreshold(LLVMPassManagerBuilderRef PMB,
1140                                               unsigned Threshold) {
1141   PassManagerBuilder *Builder = unwrap(PMB);
1142   Builder->Inliner = createFunctionInliningPass(Threshold);
1143 }
1144 
1145 void
1146 LLVMPassManagerBuilderPopulateFunctionPassManager(LLVMPassManagerBuilderRef PMB,
1147                                                   LLVMPassManagerRef PM) {
1148   PassManagerBuilder *Builder = unwrap(PMB);
1149   legacy::FunctionPassManager *FPM = unwrap<legacy::FunctionPassManager>(PM);
1150   Builder->populateFunctionPassManager(*FPM);
1151 }
1152 
1153 void
1154 LLVMPassManagerBuilderPopulateModulePassManager(LLVMPassManagerBuilderRef PMB,
1155                                                 LLVMPassManagerRef PM) {
1156   PassManagerBuilder *Builder = unwrap(PMB);
1157   legacy::PassManagerBase *MPM = unwrap(PM);
1158   Builder->populateModulePassManager(*MPM);
1159 }
1160